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ttain  Lib 


[Reprinted  from  "ClimmtoIoKy  of  CaHfornin."  Bulletin  L  U.  S.  Weather  Bureau.  ISO? 


FROST.' 


With  the  possible  exception  of  the  loss  occasioned  by  insect  pest.s,  there  is  probably  no  one 
cause  of  loss  so  seriously  affecting  crops  in  California  as  frost.  Notwithstanding  statements 
sometimes  published  that  certain  areas  arc  in  the  so-called  frostless  belt,  there  does  not  appear 
good  reason  for  believing  that  any  portion  of  the  State  may  not  be  visited  by  frost. 

The  losses  to  the  fruit  crop,  both  citrus  and  deciduous,  through  frost  have  been  so  largo 
that  special  attention  has  been  given  to  methods  of  protecting  orchards,  and  these  methods  are 
discussed  in  detail  in  the  following  pages.  With  citrus  fruits  the  frosts  of  December,  January, 
and  February  are  to  be_  guarded  against,  the  fruit  being  ripe  and  ready  for  shipment.  With 
deciduous  fruits  the  late  spring  frosts  do  the  damage.  Almonds,  apricots,  grapes,  peaches,  and 
prunes  are  hurt  while  in  bud.  or  while  the  fruit  is  just  setting,  by  the  frosts  of  March  and  April. 
The  damage  depends,  in  all  probability,  as  much  upon  the  condition  of  the  tree  as  the  degree 
and  duration  of  the  cold.  For  example,  a  sharp  frost  during  the  first  or  second  week  of  April 
sometimes  does  less  damage  if  the  trees  are  fairly  past  the  blossoming  period  than  the  same 
frosts  would  have  caused  occurring  about  the  middle  of  March. 

Attention  is  invited  to  the  excellent  table  prepared  by  Mr.  Samuel  H.  Gerrish,  of  Sacra- 
mento, giving  the  dates  of  first  and  last  light  and  killing  frosts,  also  the  dates  of  blooming  fruit 
trees  in  Sacramento  from  18t>9  to  1901. 

The  protection  of  gardens,  both  vegetable  and  flower,  is  also  important.  The  particular 
frosts  affecting  gardens  are  the  frosts  of  February,  March,  and  April,  and  it  is  pointed  out  in 
the  succeeding  pages  that  the  same,  general  principles  used  to  protect  orchards  should  be  followed 
in  the  protection  of  gardens.  A  clear,  still  night  following  thirty-six  or  forty-eight  hours  of 
boisterous  north  wind  is  likely  to  be  followed  by  frost,  particularly  if  the  movement  of  the  air 
in  the  given  locality  has  been  such  as  to  cause  a  settling  of  cold,  relatively  dry  air  strata  in  the 
hollows  or  depressions  of  the  land.  The  formation  of  frost  is  essentially  a  problem  in  air  drainage, 
and  if  by  any  means  we  can  prevent  streaks,  pools,  or  basins  of  stagnant,  cold,  dry  air  we  can 
largely  prevent  frost.  Frost  is  the  water  vapor  of  the  air  deposited  upon  the  plant  at  a  tempera- 
ture below  ;J>_i  F.  The  damage  to  plant  life  is  caused  by  the  falling  temperature.  The  water  vapor 
plays  the  part  of  an  index  only.  Indeed,  the  action  of  the  water  vapor  is  preventive.  Dry  air 
at  a  temperature  of  32°  F.  weighs  563  grains  per  cubic  foot.  Vapor  of  water  at  32°  F.  weighs  2.1 
grains  per  cubic  foot  at  a  saturation  of  100  per  cent.  Air  at  a  temperature  of  25°  F.  weighs  572 
grains  per  cubic  foot.  Given  a  little  time,  therefore,  on  a  still,  clear  night  the  loss  of  heat  by 
radiation  from  the  plant  surfaces  and  the  ground  will  bring  about  a  settling  of  the  coldeu  air  to 
the  bottom.  The  ground  will  be  covered  with  frost,  while  thermometers  6  feet  above  the  ground 
will  record  34°  or  35°  F.  Vegetables  and  flowers,  therefore,  unless  grown  upon  sloping  or  ter- 
raced ground,  are  at  a  decided  disadvantage  compared  with  tree  fruit  in  the  matter  of  frosts. 

NATI;KK  OK  KKOST. 

It  can  not  be  emphasized  too  clearly  that  it  is  the  low  temperature  and  not  the  solidification 
of  the  water  which  does  the  damage.  If  there  be  but  little  vapor  in  the  air  there  will  be  but  a 
light  frost  apparent,  and  yet  the  temperature  may  be  so  low  us  to  cause  great  injury.  The 
so-called  hard,  dry  frost,  also  called  black  frost,  does,  as  is  well  known,  even  more  injury  than 

"Since  tins  article  was  written  a  number  of  orchard-heating  devices  have  been  patented  by  various  frost 
prevention  companies  in  California.  Oil  iire  pots  have  been  tested  and  it  is  claimed  given  very  satisfactory  results. 
Gravity  oil  distillate  is  used  as  fuel  and  about  eighty  oil  pots  to  the  acre  will  insure  protection. 

L'27 


266145 


228  I'UMAToUHiY    OF    CALIFORNIA. 

heavy  frosts.  Water  vapor  at  25°  F.  completely  saturated  weighs  1.6  grains  per  cubic  foot. 
In  the  fall  from  32°  to  25°  nearly  half  a  grain  per  cubic  foot,  if  the  saturation  were  100  percent, 
would  be  condensed,  appearing  in  visible  form  as  a  frost  flake.  A  certain  amount  of  heat  was 
given  off  in  the  transformation  of  this  invisible  water  vapor  into  ice.  and  an  exactly  equal  amount 
of  heat  (known  as  the  latent  heat  of  vaporization)  will  be  in  turn  required  to  change  this  frost 
flake  back  into  vapor.  We  give  special  attention  to  this  point  because  it  would  appear  theoretic- 
ally that  the  secret  of  successful  protection  of  garden  truck  and  delicate  flowers  will  be  found  in 
this  action  of  water,  both  in  setting  free  heat  at  the  time  when  the  temperature  is  falling,  and 
on  the  other  hand  in  using  up  heat  and  thus  acting  as  a  retard  or  brake  when  the  temperature 
begins  to  rise  quickly. 

It  is  now  quite  generally  believed  that  as  much  injury  results  from  the  sudden  warming  up 
of  the  dormant  and  thoroughly  chilled  flower  or  vegetable  as  from  the  chilling  itself.  In  the 
work  of  protecting  fruits  from  frost  it  has  been  found  very  necessary  to  interpose  some  screen 
early  in  the  morning  between  the  sun's  rays  and  the  frosted  fruit.  With  flowers  and  garden  truck 
this  can  be  much  more  easily  accomplished  than  with  fruit.  In  this  respect  the  gardener  lias  a 
decided  advantage  over  the  orchardist.  The  following  is  an  excellent  statement  of  how  the  plant 
is  injured: 

HOW    FROST    INJl-KEH    PLANTS. 

Low  temperature  congeals  the  watery  part  of  the  cell  sap  and  also  the  intercellular  water  content  of  the  plant. 
Within  certain  limits  this  is  not  or  may  not  be  injurious,  providing  tin-  protoplastic  contents  of  the  cell  are  ahle  to 
absorb  the  water  and  do  this  before  the  cell  structure  collapses  as  a  result  of  insullicient  cell  turgor.  Frequently  the 
frosting  of  plants  is  followed  by  a  sudden  rising  of  temperature,  in  which  case  much  of  the  water  which  was  part  of 
the  cell  sap  in  the  normal  condition  of  the  plant  escapes  through  the  cell  wall  into  intercellular  spaces,  or  even  from 
the  plant  entirely,  and  thus,  the  protoplasm  of  the  cell  being  unable  to  assume  its  normal  condition,  Uvoiiies 
disorganized  and  decomposition  follows.  (Prof.  K.  R.  I^ake  in  the  Oregon  climate  and  crop  bulletin,  July,  1900.) 

PROTECTION  OF  ORCHARDS  FROM  FHOST. 

During  the  past  five  years  the  Weather  Bureau  office  at  San  Francisco  has  been  called  upon 
to  give  particular  attention  t<>  the  problem  of  lessening  the  injury  to  fruits  by  frost.  By  direction 
of  the  Chief  of  the  Weather  Bureau,  during  the  year  1900  the  forecast  official  for  the  southern 
half  of  the  Pacific  slope  made  an  extensive  journey  through  California  with  the  special  purpose 
of  studying  the  methods  of  protecting  deciduous  fruits  from  frost.  This  journey  was  the  natural 
outgrowth  of  the  excellent  work  inaugurated  by  Mr.  W.  H.  Hammon,  formerly  professor  in  the 
Weather  Bureau,  while  in  charge  of  the  San  Francisco  office.  During  the  years  ISH7.  is'.is,  ami 
1899  the  unusually  dry  winter  conditions,  with  frequent  and  prolonged  frosts  and  lower  tempera- 
tures than  had  been  previously  reported  in  many  of  the  chief  fruit-growing  centers  of  southern 
California,  made  it  imperative  that  some  steps  should  be  taken  to  minimixe  the  injury  to  citrus 
fruits  liv  frost.  The  problem  as  presented  to  the  forecast  official  was  of  a  twofold  nature:  First, 
a  -tudy  of  the  conditions  preceding  frost,  so  that  he  might  with  reasonable  certainty  give  timely 
warning  to  the  fruit  growers;  second,  a  study  of  the  methods,  mean-,  and  devices  for  protecting 
fruit  from  injury  by  low  temperatures.  The  first  has  been  solved  with  a  fair  measure  of  success. 
In  the  second  problem  the  Weather  Bureau  had  the  valuable  as-istanee  of  certain  practical  fruit 
growers,  who  willingly  and  readily  te.-ted  the  various  devices  proposed  for  smudging  and  cheer 
fullv  gave  this  office  the  benefit  of  the  many  practical  experiments  made  by  them  in  smudging, 
irrigating,  heating,  and  covering.  A  bulletin  on  frost  lighting,  by  Alexander  (i.  McAdie  (Bulle- 
tin No.  2'.').  was  issued  on  March  U!,  I '.«•<(.  and  nearly  Jt.ooo  copies  distributed  to  those  most 
interested  in  fruit  growing.  A  previous  bulletin  (No.  i.'!)  upon  frost,  when  to  expect  it  and  how 
to  le>sen  the  injury  therefrom,  by  Prof.  \V.  II.  Mammon,  had  been  issued  on  November  in.  is'.ix. 
while  a  Farmers'  Bulletin.  No.  I'll,  by  Prof.  K.  I?,  (iarriott.  Notes  on  Frost,  was  issued  .lime  1.',. 
Is'.t'.t.  which  treated  of  frost  protection  in  general. 

It   ha-  become  evident    in  ( 'alifornia  that   the  fruit   gn. \\erimist  possess  :i  degree  of  intelli- 
gence certainly  as  high  as  is  demanded  in  any  one  of  tin-  usual  vocations  of  life.      The  successful 


FROST.  229 

orchardist  must  be  a  skilled  farmer  and  a  good  business  man  and,  at  the  same  time,  be  familial' 
with  the  chief  principles  of  modern  science.  He  must  be  chemist,  entomologist,  and  physicist, 
us  well  as  fruit  grower.  In  the  matter  of  protecting  his  crops  from  frost,  for  example,  he  must 
know  exactly  what  method  is  best  suited  for  his  crop,  for  the  locality,  and  for  the  season,  and 
be  prepared  to  act  promptly,  or  else  the  greater  portion  of  the  year's  profits  will  vanish  in  the 
course  of  a  few  hours. 

In  what  follows  extensive  use  will  be  made  of  Bulletin  No.  29,  since  experience  has  shown 
that  the  principles  of  frost  lighting  laid  down  therein  are  essentially  correct.  While  this 
bulletin  was  written  chiefly  with  a  view  of  protecting  the  citrus -fruit  crops  of  California,  partic- 
ularlv  of  the  section  south  of  the  Tehachapi,  from  frost,  the  principles  hold,  as  a  general  rule, 
for  the  protection  of  deciduous  fruits  also. 

In  October  and  November,  1900,  an  attempt  was  made  to  extend  the  benefits  of  the  Weather 
Bureau  work  in  connection  with  frost  to  the  fruit  growers  of  central  and  northern  California, 
particularly  to  the  growers  of  almonds,  apricots,  peaches,  prunes,  pears,  apples,  grapes,  and  figs. 
Many  fruit  ranches  were  visited,  and  the  details  of  losses  by  frost  gathered  from  ranch  super- 
intendents and  others,  together  with  all  data  available  relative  to  the  exposure  of  the  fruit,  the 
lay  of  the  land,  and  the  lowest  temperatures.  The  following  facts  stand  out  prominently  from 
the  general  mass  of  statements.  First,  that  in  California  the  greatest  injury  is  done  deciduous 
fruits  by  the  late  spring  frosts  occurring  as  late  as  the  23d  of  May,  when  fruit  is  well  formed, 
frequently  resulting  in  the  loss  of  three-fourths  of  the  crop  in  the  case  of  the  more  tender  fruits, 
as  for  example,  almonds  and  apricots.  Second,  in  all  the  fruit  ranches  visited  rough  maps  of  the 
localities  showed  conclusively  that  the  frost  occurred  chiefly  in  the  low  places,  basins,  and  bot- 
toms, or  where  the  cold  air  had  drained  down  and  settled.  The  principle  laid  down  in  Bulletin 
No.  29,  that  frost  was  primarily  a  problem  in  air  drainage,  was  conclusively  upheld.  Wherever 
the  air  was  stagnant  the  injury  from  frost  was  most  marked;  and,  conversely,  wherever  the  air 
was  in  motion  there  was  little  damage  from  frost.  Fruit  on  open  benches,  hillsides,  and  terraces 
escaped.  The  streakiness  of  frost  and  the  many  apparent  irregularities  in  its  formation  can  be 
explained  easily  if  we  remember  that  there  are  currents  and  stream  lines  in  the  air,  and  that  these 
currents  may  have  rather  sharply  defined  limits.  A  slow-moving  current  of  air  on  a  still  night 
in  an  orchard  that  appears  to  be  nearly  level  may  result  in  an  absence  of  frost  along  its  path, 
while  close  by,  where  the  air  is  stagnant,  frost  will  be  formed. 

A  third  particular  point  resulting  from  this  visit  to  the  ranches  was  the  confirmation  of  the 
belief  that  the  damage  from  frost  could  be  greatly  lessened  if  some  means  were  provided  whereby 
the  chilled  fruit  could  be  protected  from  the  sudden  warming  at  sunrise.  Some  rough  tempera- 
ture observations  made  in  ranches  at  about  the  time  of  sunrise  on  frosty  mornings  showed  a  rise 
of  as  much  as  10°  in  the  air  temperature  within  thirty  minutes.  It  was  also  noted  in  several 
ranches  that  the  areas  of  greatest  loss  by  frost  were  those  where  the  sun's  heat  came  suddenly 
upon  the  trees.  It  is  believed  that  much  fruit  can  be  saved  even  when  chilled  or  frozen  if  some 
screen  is  interposed  between  the  fruit  and  the  sun,  so  that  the  warming  may  be  gradual.  It  is 
even  admissible  to  thoroughly  wet  the  fruit  with  cold  water,  and  there  are  numerous  instances 
of  fruit  escaping  serious  injury  even  when  it  has  been  covered  with  a  thin  coating  of  ice. 
It  is  of  the  utmost  importance  that  the  thaw  for  an  hour  or  two  following  sunrise  be  gradual. 

The  following  methods  of  protecting  fruit  from  frost  are  taken  from  Bulletin  No.  29: 

METHODS   OK    I'KOTEOTING. 

Every  fruit  grower  should  put  himself  in  communication  with  the  nearest  center  of  distribution  of  weather  fore- 
casts. If  possible  he  should  l>e  in  daily  communication  with  sonu-  Weather  Bureau  office.  Whenever  frost  warnings 
are  issued  for  his  locality  he  should  carefully  determine  the  temperature  and  dew-point,  as  elsewhere  described,  fre- 
quently during  the  late  afternoon  and  night.  A  good  outfit  consists  of  a.  metallic  thermometer  so  arranged  as  to 
automatically  close  an  electric  circuit  and  ring  an  alarm  whenever  the  temperature  of  the  air  reaches  32°.  In  addi- 
tion to  a  reliable  sling  psychrometer  there  should  be  some  small  device  for  testing  the  motion  of  the  gentle  air  cur- 
rents in  the  orchard.  Too  much  attention  can  not  be  given  to  this  question  of  air  motion.  Many  smudging  devices 
have  failed  to  be  effective  because  of  a  slow  movement  of  the  smoke  awav  from  the  orchard. 


230 


CLIMATOLOGY    OF    CAI.I  KOKNIA. 


1'KOTECTIVE    METHODS    H.VSK1)    <iX    MIXINli    TMK 


It  is  well  known  that  lowlands  are  visited  with  frost  while  hillsides  and  hilltops  escape.  Every  fruitgrower 
should  study  the  topography  of  his  land  and  plant  accordingly.  Wind-breaks  are,  as  a  rule,  considered  detrimental. 
No  hard  and  fast  rule,  however,  can  l>e  laid  down.  On  a  well-known  lemon  and  orange-  ranch  at  Santa  Paula,  the 


Flo.  13.— Wire  baskets  In  citrus  grove. 

property  of  Mr.  N.  W.  Blanchard,  there  are  several  large  wind-breaks  which  have  proven  themselves  to  he  of  the 
greatest  benefit  in  protecting  fruit  from  frost.  It  would  almost  seem  as  if  the  citrus  trees  within  a  distance  of  50 
feet  were  directly  protected  by  these  wind-breaks.  I?y  planting  a  wind-break  in  the  proper  place,  defects  in  the 


•  v.? 


.  1 1.— Wire  basket*  hung  Irom  limbs  of  oraugi  i 


topography  may  !H' overcome  and  air  cimei.t-  e-taMished  where  otherwise  |«>ols  of  quiet  air  would  have  formed. 
A  wind-break  dense  enough  and  HO  situated  as  to  interfere  with  any  natural  circulation  and  facilitating  the  formation 
of  still  areas  or  pools  would,  of  course,  prove  injurious. 


FROST. 


231 


PROTECTIVE    METHODS    KA.XED    ON*    WARMING    T1IK    AIR. 

A  large  number  of  small  fires,  advantageously  placed,  will  raise  the  temperature  of  the  air  several  degrees. 
The  Riverside  Horticultural  Club,  testing  the  various  methods  which  were  in  use  in  California,  came  to  the  conclu- 
sion that  wire  baskets  suspended  a  few  feet  above  the  ground,  and  holding  several  pounds  of  coal  or  charcoal,  made 
an  efficient  protector.  This  method  was  described  by  Mr.  Edward  Copely,  of  Riverside,  Cal.,  in  several  articles 
published  in  the  Riverside  Press  of  April,  ISSlfi.  The  cost  of  the  wire  basket  is  about  10  cents,  and  if  40  baskets  be 
used  to  the  acre,  the  cost  of  fuel  will  hardly  exceed  $2.50.  To  this  must  be  added  the  cost  of  labor  during  the  night 
and  succeeding  day  in  refilling  the  baskets.  In  the  accompanying  figs.  13,  14,  and  15,  the  baskets  are  shown  in 
position.  This  method  meets  with  most  favor  in  southern  California.  The  temperature  can  lie  raised  certainly  3° 
or  4°  with  from  20  to  40  of  these  baskets  to  the  acre.  It  has  been  suggested  that  a  number  of  small  oil  lamps  be 
used  with  success  for  this  purpose.  Oil  pots  have  been  used  and  make  a  hotter  fire,  but  the  deposit  of  lamp  black 
upon  the  fruit  is  objectionable.  Some  cheap  modification  of  the  ordinary  plumber's  furnace  might  possibly  lie 
devised,  which,  by  means  of  a  moderate  blast,  would  produce  a  high  temperature. 

PROTECTIVE    METHODS   BASED    ON    CLOUD    OK    FOG    FORMATION. 

Damp  straw,  old  wood,  primings,  manure,  etc.,  when  burned  briskly  furnish  an  effective  smoke,  and  if  the 
material  while  burning  is  doused  with  water  the  result  is  a  dense  steamy  smoke,  which,  while  trying  to  human 
lungs,  serves  as  a  screen  to  prevent,  loss  of  heat  by  radiation,  and  as  a  barrier  between  the  chilled  fruit  and  a  sudden 


FIG.  15.— Wire  baskets  in  lemon  and  orange  grove. 

application  of  heat  at  the  time  of  sunrise.  Wet  smudging  has  been  tried  in  many  ways  with  varying  results.  There 
are  many  reports  of  failure  and,  on  the  other  hand,  some  definite  results,  showing  the  good  accomplished  by  this 
method.  Here,  as  in  all  other  methods  of  protection,  much  will  depend  upon  a  careful  study  of  the  local  conditions. 
Many  a  farmer  smudges  so  that  some  neighbor  gets  the  benefit  of  his  work,  while  his  own  fruit  remains  unprotected. 
All  motion  of  the  air  should  be  noted  carefully,  and  this  is  sometimes  difficult  where  the  smoke  is  very  dense.  In 
some  orchards  sacks  of  old  straw  soaked  with  oil  are  so  distributed  as  to  be  available  for  quick  lighting.  Portable 
smudges  have  also  been  devised.  Fig.  1(5  illustrates  a  portable  device  by  Mr.  Priestley  Hall. 

Mr.  Hall  has  made  an  efficient  form  of  sled  operating  on  the  wet-smudge  principle.  Upon  a  sheet-iron  sled  he 
has  placed  a  small  fire  box,  consisting  of  a  grate  4  or  5  inches  above  the  bed  of  the  sled,  over  which  pass  iron  rods 
bent  in  the  form  of  an  arch,  leaving  a  space  for  the  fire  about  14  inches  in  diameter.  This  fire  box  is  inclosed  in 
a  large  corrugated  iron  box,  which  has  the  bed  of  the  sled  (about  3  or  4  feet  in  size)  for  a  bottom,  and  sides  30  inches 
high.  A  door  is  made  in  front  of  the  corrugated  box  to  admit  fuel  to  the  fire.  The  box  is  filled  with  wet  straw 
or  manure,  and  a  fire  is  maintained  in  the  fire  box  when  the  machine  is  in  operation.  The  cost  is  about  $12;  one 
will  do  for  10  acres. 

PHOTKITIVK    MKTHODS    MASED    ON    IRRIGATION. 

Of  all  methods  proposed  for  the  protection  of  fruit,  excepting  wire  baskets,  irrigation  has  the  largest  amount  of 
evidence  in  its  favor.  It  has  been  tried  in  many  different  places  with  different  crops  and  has  generally  given  satis- 
faction. Where  water  is  not  very  plentiful,  and  this  is  the  case  strangely  enough  in  some  fruit  sections,  the  method 


232  CLIMATOLOGY    OF    CALIFORNIA. 

may  not  always  lx>  practicable,  but  with  this  exception  there  are  many  decided  advantages  in  the  generous  use  of 
water.  Injury  from  frost  depends  almost  as  much  upon  the  condition  of  the  tree  as  upon  the  severity  of  the  weather. 
Critical  periods  in  the  life  of  the  tree  can  be  controlled  to  some  degree  by  the  use  of  water. 

Some  fruit  growers  hold  that  heat  is  the  one  thi.ng  that  is  desired  at  times  of  frost,  and  that  the  l>est  method  is 
that  which  produces  heat  by  the  simplest  and  least  expensive  process.      Water,  owing  to  its  high  s|>ecilic  heat,  forms 


FIG.  16.— Mr.  Priestley  Hall's  device  for  smudging. 

an  excellent  agency  for  the  tern JM  miry  storage  of  heat  energy.  \Ve  have  Been  that  in  the  wet  smudge  an  attempt  is 
made  to  utilize  the  latent  heat  of  vaporization,  and  theoretically  this  has  always  seemed  the  most  advantageous 
method.  A  modification  of  the  wet  smudge  is  steam  piped  through  an  orchard.  This  experiment  was  made  by  the 
Wright  Brothers  at  Riverside,  Cal.,  with  a  35-horsepower  boiler  and  a  main  pipe  2  indies  in  diameter,  from  which. 


FIG.  17.— Eiiflit  miner'.-,  inch.-  of  warm  water  in  orange  grove  HI  Mi-nclmm  Kunuh. 

at  right  angle-  even  1(1  feet,  pipes  three-quarter-  of  an  inch  in  diameter  were  extended.  It  is  claimed  that  the  tem- 
perature wan  raised  3°  win-never  the  steam  was  turned  on.  It  i-°  also  said  that  the  coal  consumed  would  not  be  more 
than  the  amount  used  by  the  I  a-ket  method.  The  estimated  expense  |HT  acre  would  be  about  $75. 

The  latest  di-\ice  for  the  protection  of  citrus  fruit  against  frost  combines  the  good  effects  of  irrigation  with  heat- 
iiiL'.     Tlii"  i-  :i  method  known  as  the  warm- water  method,  tried  at   Riverside.      An  account  of  the  experiment  follows. 


FROST. 


233 


KM'KHIMKXT    OF    MR.    ERNEST    A.   MKAOHAM,    RIVERSIDE,    OAL. 

"On  the  morning  of  February  It,  HHXI,  at  the  Meacham  Ranch,  a  test  was  made  of  the  Meaohain  warm-water 
method  of  protecting  citrus  fruits  against  frost.  The  experiment  began  at  8.45  a.  in.  and  was  conducted  in  the  pres- 
ence of  a  number  of  gentlemen  belonging  to  the  Riverside  Horticultural  Club,  nearly  all  of  whom  were  orange  growers. 

"At  6.30  a.  m.  the  temperature  of  the  ground  100  feet  or  more  away  from  the  boiler  was  32°.  The  temperatures 
given  herewith  are  those  obtained  by  Mr.  McAdie,  of  the  Weather  Bureau,  with  sling  psychrometer  No.  70;  the 
number  of  the  dry  thermometer  was  4487  and  of  the  wet  4486.  The  plant  consists  of  a  12-horsepower  tubular  hori- 
zontal boiler,  laid  in  a  brick  furnace  and  arranged  to  deliver  water  with  or  without  pressure.  Cold  water  enters  the 
l)ottom  of  the  boiler  and  is  delivered  f  r<  >m  the  top  orifice  directly  into  the  flume.  The  fuel  used  was  crude  petroleum, 
of  which  about  50  gallons  were  used  in  three  and  one-half  hours.  At  the  rate  of  14  gallons  an  hour  and  an  estimated 
cost  of  a  little  over  4  cents  per  gallon,  the  actual  expense  of  fuel  for  the  experiment  was  about  60  cents  per  hour.  The 
oil  is  burned  with  a  steam  jet  under  pressure.  A  secondary  6-horsepower  boiler,  carrying  70  pounds  of  steam,  was 
used.  The  oil  is  thus  entirely  consumed  and  makes  but  little  smoke.  The  whole  arrangement  is  such  that  not  more 
than  two  men  would  be  required  to  attend  to  all  the  details. 

"Fifty  minutes  from  the  time  of  beginning,  the  water  which  had  an  initial  temperature  of  55.4°  was  raised  30°. 
Two  sets  of  temperature  records  were  made,  one  by  Mr.  Priestley  Hall  and  the  other  by  Mr.  McAdie.  In  Mr.  Hall's 
test  8  inches  of  water  was  run  in  50  furrows,  which  barely  ran  ths  water  past  the  ends  of  the  furrows.  In  the  second 
case  8  miners'  inches  of  wat/r  was  delivered  into  25  furrows,  thus  carrying  the  heat  farther  down  the  furrows  than 


FIG.  18.— Lath  screen  at  ranch  of  M  r.  A.  J.  Everest,  Riverside,  Cal.  (view  from  above). 

in  the  first  experiment.  According  to  the  present  laws  of  California,  a  miner's  inch  is  .,'„  cubic  foot  per  second;  the 
'second-foot'  is  the  quantity  represented  by  a  stream  1  foot  wide  and  1  foot  deep,  flowing  at  the  average  rate  of  1  foot 
per  second.  A  cubic  foot  of  water,  maximum  density,  weighs  62.4  pounds;  a  gallon  contains  10  pounds  of  distilled 
water  at  62°.  The  data  obtained  by  Mr.  Hall  were  as  follows:  5.30  a.  m.,  normal  temperature,  34°;  normal  temper- 
ature of  water,  60°;  temperature  of  heated  water,  92°;  at  the  flume,  P2°;  20  rods  from  the  flume,  58°;  40  rods,  52°; 
temperature  of  unheated  water  40  rods  from  the  flume,  41.5°;  vapor  condensed  on  trees  early  in  the  morning  and 
more  condensed  on  the  trees  in  the  heated  plat. 

"Mr.  McAdie' s  records  are  as  follows:  Time,  6.30  a.  in.,  air  temperature  varying  from  .'!4°  to  36°;  temperature 
on  the  ground,  32°;  frost  was  observed  on  grass  blades;  initial  temperature  of  water,  55.4°;  heated  water  delivered 
to  flume  at  85.2°;  in  a  straight  line  down  a  furrow  200  feet  from  the  boiler  in  the  direction  of  the  wind  (motion  of 
the  air  was  very  gentle)  there  was  a  fall  in  temperature  of  14.2°;  water  vapor  was  observed  rising  to  a  height  of 
about  4  feet;  200  feet  from  flume,  as  stated,  the  temperature  of  the  water  was  71°;  the  temperature  of  the  surface  soil 
4  inches  right  and  left  of  the  water  was  43°;  temperature  of  the  soil  16  inches  from  the  water  or  in  the  middle  of  the 
ridge,  42.2°.  It  is  presumed  that  the  temperature  of  the  ground,  had  no  water  been  flowing,  would  have  been  33°, 
and  it  would  seem  as  if  the  soil  itself  was  warmer  by  nearly  10°.  At  the  end  of  a  furrow,  600  feet,  the  temperature 
of  the  water  was  54°,  or  there  had  been  a  fall  of  31°  in  40  rods;  the  temperature  of  the  ground  4  inches  from  the 
water,  38°;  16  inches  from  the  water,  36°;  temperature  of  unheated  water  50  rods  from  the  flume,  40°. 

"The  approximate  value  of  the  plant  was  $200,  and  it  is  estimated  that  for  a  plant  all  equipped  sufficient  for  a 
10-acre  grove  $600  would  cover  all  expenses."  (See  fig.  17. ) 


234 


CLIMATOLOGY    OF    CALIFORNIA. 


SPRAVIM.. 


Alt  IT  frost,  or  rather  just  before  a  fro«t  has  ended,  a  spraying  device  can  be  used  to  ad  vantage.  Its  chief  function 
is  to  prevent  a  too  rapid  warming  of  tin-  chilled  fruit.  It  is  said  by  horticulturists  that  even  the  light  coating  of  ice 
formed  in  this  way  does  not  seriously  damage  the  fruit.  It  is  very  likely  that  the  latent  heat  of  solidification  set 
free  by  the  change  from  water  to  ice  may  play  a  helpful  part;  but  the  chief  effect  is  to  prevent  a  too  rapid  thawing. 
In  other  words,  both  heat  and  water  should  be  supplied  to  the  chilled  plant  slowly  and  according  to  the  plant's 
ability  to  make  good  use  of  the  same.  At  the  A.  J.  Everest  Ranch  at  Riverside,  Cal..  a  portion  of  the  grove  is  pro- 
tected by  sprinklers  at  the  top  of  50-foot  masts. 


Flo.  IS).— Lath  screen  m  much  of  Mr.  A.  J.  Everest,  Riverside',  Cal.  (under  view). 
PROTKCTIVK   MK-moim   BASED  VPON  SCREENING   OK   COVERING. 

All  screening  or  covering  devices  are  in  effect  modified  hothouses,  ami  there  in  no  question  but  that  a  thorough 
protection  can  be  accomplished.  The  expense  is  the  one  objection.  Screens  are  made  of  light  materials,  namely, 
canvas,  muslin,  or  light  wood  work,  and  .have  been  used  \\ith  considerable  success.  At  the  A.  .1.  Kverest  Ranch  an 
elaborate  structure  of  lath  screens  is  in  use,  illustrations  of  which  are  given  herewith  (see  figs.  IS  ami  lit).  There 
is  no  question  as  to  the  value  of  the  protection,  but  the  expense  is  considerable,  averaging  perhaps  $400  to  the  acre. 
This  lath  covering  may  be  considered  as  forming  a  well-ventilated  hothouse. 


FROST. 
KILLING    FROSTS. 


235 


The  following  table  gives  the  dates  on  which  occurred  killing  frosts  during  the  year  1899 — 
the  last  in  spring  and  first  in  autumn — at  stations  recording  and  reporting  frosts.  The  blank 
spaces  in  the  table  indicate  that  there  were  no  killing  frosts  at  those  stations  for  the  period 
shown,  or,  in  some  few  cases,  that  the  record  is  incomplete. 


Station. 

Killing  frost. 

Station. 

Killing  frost. 

Station. 

Killing  frost. 

Last  in      First  in 
spring,     autumn. 

Last  in 
spring. 

First  in 
autumn. 

Last  in 
spring. 

First  in 
autumn. 

Mar.  10 

Dec.     2 

Nov.  23 
Do. 
Oct.      6 
Dec.  12 
Dec.     3 

Oct.    31 
Oct.    15 

Dec.     9 
Dec.    6 
Dec.  18 

Oct.     2 
Oct.    24 
Nov.  16 
Oct.    28 
Dec.  18 
Dec.     2 
Oct.    25 
Oct.     1 
Dec.   18 
Nov.    8 
Dec.  20 
Oct.     2 
Dec.  12 

Dec.     5 

Oct.      9 

Oct.    14 
Dec.     9 
Dec.     1 
Dec.  19 
Nov.  27 

Dec.  19 
Dec.     9 
Oct.    15 
Oct.    11 
Dec.   10 
Dec.     6 
Dec.  20 

Oct.    26 
Dec.  10 
Dec.     7 
Dec.  13 

Dec.     6 

Mar.  12 
Feb.     8 
Mar.  18 
Mar.  21 
Feb.     7 
Mar.    9 
May     1 
Mar.  11 
Feb.     7 
Apr.  29 
Mar.  18 
May     1 
Apr.   29 
Mar.  13 
Apr.   17 
Feb.     5 
Mar.  18 
Mar.  17 
Apr.   28 
Apr.   23 
Mar.  19 
May    11 
Apr.   28 
Feb.     5 
Apr.   23 
Mar.  12 
Mar.  18 
Feb.  22 
Mar.  11 
May  25 
Mar.    7 
Mar.  10 
Mar.    8 

Dec.  10 
Dec.  18 
Oct.     15 
Dec.  18 

Nov.  23 
Oct.    15 
Dec.     6 

Oct.     1 
Oct.    15 
Dec.     9 

Dec.     9 
Oct.    13 
Dec.     6 
Oct.    12 
Dec.     9 
Oct.   15 
Dec.     1 
Oct.    15 
Oct.     7 

Dec.     9 
Sept.    6 
Oct.    24 
Nov.  22 

Oct.    15 

Dec.     9 
Do. 
Dec.   10 

Dec.  18 
Dec.  10 
Dec.  17 
Dec.     1 
Dec.  20 
Nov.  30 
Dec.  20 

Dec.  10 
Dec.  17 
Dec.  19 

Oct.    15 
Dec.  18 

Oct.   24 
Dec.     9 

Oct.    30 
Oct.    15 

Feb.     4 
Mar.  10 
Feb.     8 
Apr.  23 
Mar.  10 
Apr.  28 
Mar.  14 
Mar.  10 
Feb.     7 

Dec.  19 
Do. 
Do. 
Dec.  20 
Dec.   18 

Dec.     9 
Dec.  10 
Do. 
Do. 
Aug.  22 
Dec.     1 
Dec.  19 
Dec.  14 

Dec.     6 
Do. 
Dec.  18 
Dec.     6 
Dec.     9 

Dec.  27 

Dec.   18 
Dec.     7 

Nov.  27 

Dec.  19 
Dec.  20 

Dec.  14 

Oct.    24 
Oct.     2 
Dec.  19 

Dec.  10 
Dec.  13 
Dec.    9 
Dec.  19 
Dec.  18 
Dec.  19 
Oct.    12 

Dec.  13 
Dec.     4 
Sept.    6 

Folsom  .                        .  . 

Feb.     7 
May     2 
Mar.  18 
May  15 
Apr.  17 
Apr.  30 
Feb.  10 
Mar.  10 
May     2 
Feb.     C 
May     1 
Mar.  10 
Jan.     5 
Mar.  10 
May     1 

Palo  Alto 

Fort  Ross  

Fruto        ...              .... 

Gilroy  .      .             

Porterville 

Puente 

May  20 
May  22 

Biivles  

Red  Bluff 

May     1 
Feb.     5 
Apr.  28 
Feb.     9 
Mar.    3 
Mar.  13 
May  16 
Mar.  12 
Feb.     5 

Berkeley  

Hollister 

Boca  

Iowa  Hill 

Bowman's  Dam  

May     1 
Mar.    4 

Rocklin 

Bvron  

Feb.  12 
May     9 
May    1 
Mar.  10 
....do... 

Cah  to  

Calistoga  

Campbell  

La  Porte 

Feb.     5 
Jan.   26 
Mar.  10 
Feb.     4 
Feb.     7 
Feb.     9 
Mar.  17 
Feb.     6 
Apr.     3 
Feb.     7 
Mar.  17 

Capitola  

Castroville  

Cedarvillu    

May   18 
Mar.  30 
Feb.     6 
May     1 
Feb.     7 
Feb.     6 
May  10 
Feb.     6 
June  19 
Mar.  28 
May   20 
Feb.     7 
May     2 
Feb.     7 
do 

Chico  

Claremont  

Colfax  

Colton  

Ixxii                           .  .  .. 

Corning  

Craftonville  

Feb.     7 
Feb.     6 
Mar.  11 

Feb.     7 

Crescent  City  

Menlo  Park 

Cuyamaca  

Feb.     7 
Mar.  13 
Feb.     6 
Feb.     8 
May    2 
May  25 
Apr.  30 
Feb.     5 
Mar.  12 
Feb.     5 
do 

Danville  

Milbrae 

Davisville  

Mills  College  

Soled  ad 

Dinuba  

Milo  

Apr.  10 
Apr.  28 

Duarte  

d 

Dunnigan  

Durham  •.  . 

Mar.  13 
Apr.   29 
May     2 
Feb.     7 
Apr.  26 
....do... 
Mar.  10 

May  16 
Mar.  10 
Feb.     6 
Mar.  13 
Feb.     5 
May     1 
Mar.  10 
Apr.  29 
May     2 
Miir.  13 
Mar.  18 
May     2 
Feb.     5 
Apr.  20 

Edgewood  

Edmanton  

T 

El  Cajon  

Ukiah 

El  Casco  

El  Dorado  

Nevada  City 

Vacaville 

Feb.     9 

Apr.   UK 

Elk  Grove  

Elmira  

Niles 

\V-itM>nville 

Elsinore  

Mar.  12 
Mar.  18 
Feb.     7 
Feb.     6 
Feb.     8 
Mar.  13 

North  Bloomfield 

May  L>» 
Feb.    3 
Apr.     1 
Apr.  26 
Apr.     2 
May  20 

Escondido  

"North  Hill  Vineyard  

Eureka  

Exeter  

Willows 

Fall  Brook  

Oakland  

Woodland 

Farmington  

Oleta  

Yreka 

NOTE.— Killing  frosts  occurred  in  every  month  of  the  year  at  Bodie,  Mono  County.  The  observer  at  Los  Angeles  reports  that  there 
were  no  killing  frosts  at  that  station  during  the  year;  the  first  heavy  frost  occurred  December  11,  damaging  vegetables  in  exposed  places. 
At  San  Diego  the  most  severe  frost  for  five  years  occurred  February  6,  but  did  not  damage  orchards  or  fruit  in  citrus  region. 


236 


CLIMATOLOGY    OF   CALIFORNIA. 
10OO. 


Stations. 

Eleva- 
tion. 

LU--I  in 
spring. 

First  in 
autumn. 

stutiims. 

Kleva- 

linii. 

l.as!  in 
spring. 

First  in 
autumn. 

Feet. 
134 

Mar    13 

Dec    29 

Pat. 
660 

Kfb       7 

Angiola  

208 

Feb.  10 

Dec.  27 

North  Ontario  

i.soo 

Dec    29 

Feb     8 

Dec    31 

'1  130 

Mar    20 

Bear  Valley                               

4,600 

May  15 

Oct    12 

Oakland 

M 

Dec    30 

Apr    23 

Sept  26 

Oleta 

1  510 

Apr     8 

Berkeley                                                 

320 

Feb.  19 

Dec    30 

Oroville 

188 

.Inn     "4 

Bodle  

8,248 

June    2 

Aug.    7 

Palermo 

l.HT) 

Dec    23 

5,500 

Mav  25 

Sept.  20 

723 

Apr    'Jt> 

Oct      30 

Campbell             

194 

Apr.     8 

Dec.  28 

Peachland  

220 

Dec    28 

Apr.   10 

Sept  26 

Pilot  Creek 

4  000 

Sept  20 

CedarvilU'             

4,675 

Apr.  27 

Sept.  18 

I'liieerville  ... 

1  820 

Feb      7 

Nov   28 

Chico 

193 

Apr.   10 

Dec    28 

Pollasky 

1  200 

do 

Dec    28 

423 

Mar.  28 

Nov.  27 

857 

Kcli     12 

Dee     17 

1  759 

Feb.     4 

Dec    29 

Porterville 

4(U 

Fch     11 

Dee     •'* 

Crescent  Citv                  

50 

Apr    26 

Nov.  20 

Quinrv  

3,350 

Mav    "M 

Sept      f> 

Cuddeback 

Apr      6 

Dec      4 

Redbluff 

307 

Dec    29 

4,543 

Apr.  30 

Sept.  26 

Redding  

r>!>7 

Feb.     9 

Dec     3 

Delta 

1  138 

Feb     9 

Sept     6 

Redlands 

1  335 

Apr      t 

Dec    31 

790 

Feb.     6 

Dec.  28 

865 

Apr.   10 

Dec    23 

180 

Mar    28 

Dec    23 

35 

Dec    31 

4  750 

Apr    24 

Oct.    29 

236 

Apr.   10 

Dee     ••" 

1  609 

Apr      9 

1  054 

Dec    31 

126 

Jan      9 

Dec    27 

183 

Dee     ::<> 

Klmira                                      

75 

Feb.     8 

Nov.  30 

San  Jacinto  

l,f>00 

Apr.    12 

Oct.    28 

1  271 

Apr      8 

Dec    29 

84 

Dec    30 

111 

Apr.     4 

Oct.    29 

San  Luis  Obispo  

201 

Apr.     H 

Dec.  29 

182 

Dee     ::n 

San  Miguel 

616 

Feb.  10 

7  Ii50 

Apr    10 

Oct     24 

137 

Dec.  28 

293 

Dec.   81 

anta  Clara  

88 

Apr.    9 

Dec.  31 

Garberville 

May     1 

Dec    28 

IK 

Mar.  27 

Dec      -2:'. 

2,750 

Apr.     8 

Nov.  19 

Santa  Maria  

220 

Apr.   10 

Dee.     Ki 

Gilrov 

193 

Apr      9 

Dec    23 

2KI1 

Dec.  30 

65 

Jan    25 

Dec    30 

181 

Oct     29 

3  600 

May  2H 

Oct      1 

Shasta           

1.1  is 

Nov.   21 

249 

Feb    26 

Oct.    25 

Sonoma  

30 

Apr.     9 

Dec.  30 

100 

Oct     29 

Stanford  rniversitv    

70 

Apr.  10 

Dec.  31 

Hollinter 

284 

Apr    10 

Dec      4 

Stockton  

33 

Do. 

::  'my 

Mar     7 

Oct     30 

Suisun  City       

20 

Feb.  12 

Dee     •_':: 

287 

Feb      8 

Dec    28 

5,270 

May  2S 

Sept.  25 

Iowa  Hill                                   .  . 

2,825 

Mar.    5 

Dec.  31 

Susanville  

4,195 

Apr.  27 

Sept.  24 

1  975 

Apr     8 

Oct    29 

Tequisquita  Rancho  

Apr.   10 

Dec.  23 

d» 

Oct    23 

Thebe  

Mar.  15 

Oct.     1 

KeniTille 

2  600 

Mav     9 

Sept  27 

236 

Dec.  30 

1  325 

Dec    28 

Tulare  

•J7I 

M.ir.  is 

Oct.    30 

5  000 

May  28 

Sept     6 

Uklah 

620 

Apr.     9 

Dec.  2« 

256 

Apr     4 

Dec.  27 

Vacavillc  

in 

Feb.     7 

Dec.  29 

4,209 

Oct.     2 

Valley  Springs  

673 

Mar.  27 

Do. 

Lodi 

35 

Apr      9 

Dec    29 

Vina  

213 

Apr.     2 

Apr.  26 

Nov.  15 

Visalia  

:::•.! 

Apr.  10 

Dec.  28 

Merced 

178 

Mar    28 

Dec    30 

Wataonville  

23 

Apr.     8 

Mokelumne  Hill 

1  560 

Apr     8 

Dec      2 

West  1'oiiii 

2,  326 

Apr.     '.l 

Oct.     7 

3  100 

Apr    29 

Oct     30 

Whentland            

84 

do... 

Dec.  28 

20 

Feb     6 

Dec    30 

Wire  Bridge  

565 

....to... 

Dec.  23 

2  580 

Apr    27 

Woodland                       .          

M 

Mar.     5 

Nov.  29 

Xiles  (near) 

87 

Apr     9 

IK,     ::<> 

Yreka  

•>,<\x< 

Mar.  2<J 

Sept.  30 

3  000 

Apr    14 

Oct     29 

Ynba  Citv                            

7" 

.Inn.    21 

Dee.    2V 

FROST. 
AVERAGE  DATES  OF  KILLING  FROSTS. 


237 


Stations. 

Counties. 

Ek'vii- 
tion. 

Average  date. 

Stations. 

Counties. 

Eleva- 
tion. 

Average  date. 

Last  in 
spring. 

First  in 
autumn. 

Last  in 
spring. 

First  in 
autumn. 

Feet. 
134 
320 
5,500 
194 
4,675 
1,200 
60 
180 
4,750 
1,271 
04 
293 
100 
284 
3,907 
2,825 
1,975 
35 
1,550 
20 
3,000 
660 

Apr.     4 
Jan.   28 
Apr.  26 
Mar.  25 
May  15 
Mar.  17 
May    10 
Apr.     5 
May  10 
Mar.  23 
Mar.  29 
Mar.     1 
Apr.     » 
...ido... 
Mar.  23 
Mar.  15 
Apr.   15 
Mar.  12 
Mar.  21 
Mar.  20 
Apr.    17 
Fell.   20 

Dec.  20 
Dee.  15 
Oct.  25 
Nov.25 
Oct.    6 
Dec.  5 
Nov.  7 
Do. 
Oct.  22 
Nov.26 
Nov.29 
Nov.15 
Nov.16 
Nov.21 
Oct.  25 
Dec.  16 
Oct.  25 
Nov.16 
Dec.  15 
Nov.15 
Do. 
Dec.  13 

San  Bernardino  .  . 

Feet. 
1,800 
2,130 

14 
1,510 
723 
220 
857 
3,350 
307 
1,000 
865 
35 
183 
201 
220 
5,270 
4,  195 
620 
175 
84 
2,635 

Mar.  14 
Apr.  11 
Jan.     7 
Mar.  20 
Apr.     1 
Apr.   14 
Apr.     2 
May   15 
Mar.  27 
Mar.  17 
Apr.     8 
Feb.  16 
Jan.   25 
Mnr.     5 
Mar.  10 
May     7 
May  10 
Apr.  14 
Mar.  12 
Feb.  20 
May  24 

Dec.  14 
Oct.    15 
Dec.  20 
Nov.  19 
Nov.    5 
Nov.  21 
Nov.  20 
Sept.  14 
Dec.  16 
Dec.  20 
Nov.    7 
Nov.  15 
Dec.  10 
Nov.  18 
Nov.  26 
Oct.    17 
Sept.  22 
Nov.    1 
Dec.  21 
Nov.  26 
Sept.  26 

Berkeley. 

Alameda  

Oakland 

Campbell  

Santa  Clara  

Oleta 

Cedarville 

Modoe  .. 

Paso  Robles  (near)  .  .  . 

San  Luis  Obispo  .  . 

Claremont  

Los  Angeles  

Durham  

Butte  

RedblufT 

Elsinnre  
Eureka  

.Riverside  
Humboldt. 

Riverside  

Riverside  

Fresno  

Fresno  

San  Francisco  
San  Luis  Obispo  .  . 
Santa  Barbara  

Hollister 

Santa  Maria  

Iowa  Hill  

Placer  

Susanville  
Ukiah  
Vacaville  

\Vheatland 

Lassen  
Mendocino  
Solano  
Yuba 

Lodi 

Mokelumne  Hill  
Napa  (S.  H.)  

Calaveras  

North  Bloomfleld  .... 
North  Hill  Vineyard. 

Nevada  
Calaveras  

Yreka  

Siskiyou 

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— — —~^~~ — -^___ 


\SUM 

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LD  21-100m-l.'54(1887ll6)476 


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UNIVERSITY  OH  CALIFORNIA  LIBRARY 


